Combined internal-combustion and hot-air engine.



APPLIGATION FILED APR.3,191 1.

Patented May 19, 1914.

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COMBINED INTERNAL COMBUSTION AND HOT AIR ENGINE. APPLICATION FILED APR. 3, 1911,

i1 ,097,068. Patented May 19, 1914.

4 SHEETS-SHEET 24 nj Eil -l W/TNESSES.' 1 /lVl/E/VTO? (fw/n Wazaa/7m Jmqygha W. J. WRIGHT. COMBINED INTERNAL COMBUSTIONy AND HOT AIR ENGINE. APPLICATION FILED APR. 3. 1911.

1,097,068. Patented May 19, 1914.

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Q\ b E W. J. WRIGHT.

APPLICATION FILED APN. s. 1911.

COMBINED INTERNAL ooMBUsTloN AND EOT AIE ENGINE. 1,097,068.

narran sirenas arena orion WILLIAM a. WRIGHT, or raaNIiLIN, PENNSYLVANIA, assIeNon 'ro ware-IIT ENGINE coIvIPaNY, or PITTSBURGH, PENNSYLVANIA, a ccarona'rIoNor DELAWARE.

-COMBINED INTERNAL-COMBU'STION; AND HOT-.AIR ENGINE.

' Specification of Letters Eatent.

' raeentea May Is, raie.

Application filed April 3, 1911. Serial No. 616,687.

To all who/n it 'may concern Be it known that I, WILLIAM J. WRIGHT,

residing at Franklin, in the county of Venango and Stateof Eennsylvania, have 1nvented certain new land useful Improve- 'lhe present Invention relates to internal combustlonengines of the compound type and it employs a high pressure cylinder and-y its piston, operating generally onL the fourcycle principle, while still obtaining two working impulses in each'cycle; 'a low .pressure cylinder and its piston also operating on the four-cycle principle, obtaining two working impulses to each cycle of operation; a fuel charging pump; an air chargingr pump; and the necessary v alves and valve gear, ports, etc., to effect the required operation.

The invention also includes a method and means for drawing the heat out of the cylvinder walls, utilizing the expansive force thereof in performing work on both pistons during a partcf their cycles of operation,

thus enabling much of the energy that is lost in other types of engines in the shape of heat, to be conserved aswell as effectively cooling `the cylinders, andthus enabling a higher initial compression to be applied without danger of remature explosion:

Again, it is thc o ject of my invention to provide `means whereby a maximum initial density of the new mixture may be obtained prior to ignitiomsothat the initial pressure of the red mixture will rise to a maximum; in other words, by combining pressure and simultaneously cooling the new charge and the cylinder walls',-a-maximum densityof working agent is obtained whereby the force of expansion when ignition takes place4 will be considerably greater than has heretofore been found possible in engines of the internal combustion type. Furthermore the heat 4 of combustion being diii'used throughout the cylinder walls, and its energy lost by radiation and conduction, the heat is drawnv out of the cylinder walls, by the air charge,`

thereby causing the air to expand and do work. c engine operates during one part of its cycle as an internal combustion engine, and during another part of its cycle as a heat engine, thus utilizing the advantages of both^types while 'obviating their disadvantages,

The invention lalso includes an improved method of operating an internal combustion lengine whereby the heat that is usually wasted is employed to do work, thus avoiding the necessity of providing cooling jackets tov convey away the heat, and on the other hand, conserving a large part of the heat energy and making it do work on the pistons during a part of their cycle of movement. i l

The invention further has for its obj ect to cause the vheated air to act not only on the low pressure pistons, but also on the high pressure piston during a part of the cycle of operation and without admitting a new charge of fuel into the cylinder. l

Another object of'my invention is to admit the fuel into the high, pressure cylinder intermediate the ends off/the' working cham- .berl during the time the Ihigh pressure piston .1s moving on its u Vstroke to compress the contents of the hig pressure cylinder ahead of it, andw/hile'thevhigh pressure cylinder contains fresh air, thereby causing the fuel to enter the cylinder between two strata of air -as it were, the air serving to draw the heat from the cylinder walls and piston head and impart some of it to the fuel charge. This keeps the high pressure cylinder as cool as possible, enables a longer stroke to be employed and permits a .high initial compression to be given to the c argc without premature firing thereof, than is possible with the ordinary types of engine.

. My invention also includes those novel details 'of construction, combination and arrangement` of parts, all of which will 'be first fully described, then specifically pointed' out in the appended claims, and illustrated in the accompanying drawings, in which:

Figure 1, is a top plan view of my enginecomposed of a double'unit. Fig. 2, is a vertical longitudinal section on the line 2-2 of Fig. 1. Fig. 3, is a diagrammatic view of the same. Figa, is a diagrammatic -view of the various positions of the valve actuating cam when the respective valves are open. Fig. 5, is an enlarged detail section of the by-pass valve and the duct of thefuel pump. Fig.` 6, is a detail view ofthe oiling system and oil pump. F ig. 7, 1s a `diagrammatic view indicating the cycles of operation of the high pressure piston, the low pressure piston, the-.air pump piston, and the fuel ump., Fig-8 is a" detail side elevation andp part section hereinafter referred to. Fig. 9 is a detail eleva-tion of` a portion of the invention.

Referring'now t0 the accompanylng drawings, in which like letters and numerals of reference indicate like parts, in all of the figures, 1 and 15 are the low pressure cylinders in which the low pressure pistons 3 and 17 respectively, operate. The high pressure cylinders 2 and 16 contain the high pressure pistons 4 and 18 respectively.

5 is the crank shaft which-is common to all of the pistons and has cranks 6, 7, 19 and 20, to which the connecting rods 8, 9, 21 and 22 to the pistons 3, 4, 18 and 17, respectively are joined.

10 and 23 designate the exhaust ports of the low pressure cylinders 1 and 15 respectively and the exhaust ports 10 and 23respectively are controlled by exhaust valves -11 and 24 respectively. See Figs. 1, 4 and 8.

13 and 26 designate the valves in they bypasses 12 and 25'in the cylinders 1 and 2 and 16 and 15 respectively, the valves 13 and 26 being 'in the head of the cylinders 2-and 16 respectively.

rlhe high pressure cylinders 2 and 16 have piston. controlled air inlet `ports 14 and 27 respectively that'are opened when the pistons 4 and 18O respectively are at the lowermost limit of their strokes. l At the upper end the pump 28 hasa duct 30 that .cominunicates with the duct 25 at the end nearest the high pressure cylinder16, the duct 4 30` having a back check valve "49, as indicated. The lower end of the pump 28 is in communication with the duct '12 between the cylinders 1 and 2, through a duct 31l that en- 'ters the duct 12 over the high pressure cylinder 2 and contains a back check valve 49. Thus the pump 28 serves to supply air to the low pressure cylinders 1 and 15, through theY ducts 12 and 25, and operable, as will later be described. l

The pump 28 includes the piston 32 that is double acting and has itsrod 33 projected into the fuel pump casing 34 and joined to the fuel piston 35, which is in turn connected by a rod 36 with a cross head 38 which is driven by a crank 41 on the shaft 5, to which `a connecting rod 39 is joined at 40. A I charge of air and gas is admitted to each end -and the ducts 42 communicate with "the air of the cylinder 34 of 'the fuel pump through ducts 42. in which are back check. valves 49,

and gas inlet ducts 43 and 44 respectively through valve laterals, asindicjated .in 'Fig'. 3 of the drawings. Fuel is 4conveyed from the upper end of the cylinder 34 to the high pressurecylinder 2, through a` piston-controlled 'port46 with which the ducts 45 communicate, a back check valve 49 being provided in the duct 45. The lower end of the pump 34 communicates with the high pressure cylinder 16, at its port 48 through the medium of a duct 47 in which is a back check valve 49, for the usual purpose.

In my present engine, the pump 35 operates to inject fuel'into the high pressure cylinders on alternate strokes of the saine, that is, once in every other stroke, and as the pump piston 35 makes one stroke for each stroke of the pistons 4 and 18, it is necessary that the charge be shifted from one end of the pump cylinder to the other, on alternate strokes so as not to force the fuel into the high pressure cylinders except onv alternate strokes. I' have therefore provided a bypass duct 50 which communicates at 51 with the respective ends of the cylinder 34 and contains two valve seats 52 and 53'respectively, which are closed by the valves 54 and 59 respectively. The valves 54 and 59 are controlled by a valve actuating rod 62 on which the valves 54 and 59 have loose engagement. The valve 54 has its stem 55 projectedrinto a socket 58 ofthe rodvv 52 and is held normally closed by a spring 57 that engages a spider in the duct 50 anda collar 56 on the stem 55. The valve 59 is normally closed by the spring 60 and is opened by a projection -or collar 61 on the rod 62 that engages the valve 59 at intervals, the shoulders off the socket 58 engaging the collar 56 of the valve 54 to open'it on the up-stroke of the rod 62 while the collar 61 opens the valve 59 on itsl down stroke. The rod 62 is reciprocatedj.

once to every two reciprocations of the piston 35 by a two to one gear connection 64-65 with the shaft 5, the gear 64 carrying a crank 63 to which the rod 62 is connected as shown.

66 are the cams that operate the valves 11 and 13, there being one cam for each set of valves 11 and 13. The cams 66 are so set open about the distanceof 115.v `Thevalve 13 opens on the down' 'stroke ofl'the piston 4 after it has gone about 509.011 such down stroke and remains openhuntil the piston 4 goes'on its up stroke` the distance of about 40, more or less. The valve 26 operates in the saine manner -as the valve 13, and the valve 24 operates in the same manner as the valve 11. the difference being that the open;

that the valve 11 will commence to open afterthe piston 3 has started on its up stroke 'a distance of about 10, the valve remaining" ing of the valve 26 occurs 180 after the valve 13 opens and the valve 24 opens 180 .after the valve 11 opens and vice versa. In

other words the operation of the'valves 13 and 26 and 11 and 24 are 180 apart.

67 designates the cam engaging portions of the valve actuating rods 68 which join .cylinder head, the rocker arms 73 and 75 being provided -with"hushers or noisepreventing devices 74.

77 designatesan oil pump whose piston is connected by a rod 80 to the crosshead 69 or other' reciprocating part of the machine and the pump 77 conveys oil from the reservoir 78 to the piping 79 that distributes the oil to bearings as indicated, the reservoir 78 receiving the overflow -oil from the crank case through overflow pipe 81.

Having thus described the construction of my engine, the method of operating the Asame will be best explained by reference to Figs. 3 and 7. Assume the parts to be in positions as indicated inTFig. 3. There will be a charge of cold air in the cylinder 1 ahead of the piston 3 which is about to be forced in by the piston 32, via ducts 31 and 12 over the cylinder head 2. The incoming' air draws the heat out of the walls of the cylinder 2 andthe walls of the cylinder 1, a-nd the air thus becomes somewhat warm as it is forced into the cylinder 1, so that on lthe down stroke of the piston its expansive force may be utilized. There will be a charge of compressed new fuel mixture and air in the cylinder 2 ahead of the piston 4 which is just about to begin its down stroke and thecharge ahead of it is just about to be ignited. The piston 17 will be moving on its down stroke, the valve 24 closed, the valve 26 open, and the piston 17 is drawing the old charge of exploded working agent'from the cylinder 16- into the cylinder 15, via the duct 25, and at the same time drawing cold air into thel cylinder 16 through the port 27. Now as Athe piston 4 moveson the down stroke it will move under the influence lof the exploded new charge in the cylinder `2 until it reaches the ports 14, at which .time

' the exploded charge will be at approximately atmospheric ressure. As soon as the piston 3 has'comp eted its up stroke and started on its down stroke the expanding air will exert a pressure against the piston/.to move it' on its down stroke, and after it begins to move on its down stroke the expanding 'air will be reinforced bv the charge from the cylinder 2, which will be admitted into the cylinder 1 after the piston 4 has moved vdown about 4 5 orv 50 degrees, lat which time, the valve 13 will open so that both cylinders 1 and 2 will .be thrown into communication and both pistons 4 and 3 will be im-pelled together for a distance of about 90 more or less until the piston 4 be-l gins to open the ports 14, at which time Jthe remaining portion of tne down stroke of the piston 3 is utilized to dra-w the old charge of burnt fuel from the cylinder 2 via duct 12 into cylinder 1, and at the same time draw air into the cylinder 2 through the ports 14. The valve 13 remains open until thepiston 4 starts on its up stroke and covers the ports 14, after which the valve 13 closes. The piston 40u its up stroke then com-presses the charge of air which has been drawn in through the ports 14. The piston 3 on its up stroke exhausts the old charge through the port 10, the valve 11 starting to open just 'after the piston starts on its up stroke, and remains open until the piston has passed through about 115 or 120 degrees on its 11p-stroke, or in other words, until it arrives at the posit-ion shown in Fig. 3, atl which time the valve 11 closes, and at this time also, the air from the pump ,28 is ejected through 4the duct 31 into the duct 12 and into the cylinder 1, the air entering until a balance of pressure in the duct 12 and the pump 28 is reached, at which time the back check valve 49 in the duct 31 closes, and the remaining part of the up-str'oke of the piston 3 isutilized to compress this air charge. vThe pump 32 forces air into. the cylinder 1 on each down stroke of the piston 32, as described. Now, as the piston 4has completed its up-stroke it will move 'Y downwardly under the influence 'of the compressed charge of air drawn in through the ports 14 which has taken up the heat of the walls of the cylinder 2 and thus expanded exerting aforceon the piston 4 which now operatesas a hot air engine. As the piston 3 reaches the limit of its upstrokev and starts on its down stroke it will operate as a hot air engine under the expansive force of the air `pumped in by the pump 32 and heated `in passing over theihead of the cylinder 2. After the piston 4 has moved on its down stroke a distance of about 45 or 50 degrees, the valve 13 again opens and the cylinders 1 and 2 are again thrown 1nto communlcation, thus allowing both pistons 3 and 4 to operate through a further distanceof together as hot air engine pistons under the influence of the expanding air that is within the cylinders and l.has drawn the heat out of the cylinder walls'. As the piston 4 opens the ports 14 the piston 3 will again draw the contents of the cylinder 2 through the duct 12 int-o the cylinder 1 and -draw air into the cylinder 2 through the ports 14. After the piston 4 has closed the'ports 14 on its second 11p-stroke itwill compress the air in the cylinder 2; the valve \13 will close and the piston 3 in starting on its up-stroke will exhaust the said air from the cylinder 1 through the port 10, the valve charging pump 35 will force a charge. of fuel v through the duct 45 into the. cylinder 2, ahead of the piston 4. which charge of fuel plus the air in the cylinder 2 will be compressed during the remaining ortion of the tip-stroke of the piston 4. A r the pist-on 3 has moved up the required distance and exhausted the old air charge, the ump 32 will again pump a charge of resh air through thedfiict l2 into the cylinder l, further cooling the 'eXplosioncham-ber end of the cylinder 2 in which th'e new charge is being compressed and conveying the heat into the cylinder 1, where the air is com-A pressed during the remaining part of the lip-stroke of the piston 3. As the piston 4 roaches the limit of its up-stroke and starts on its down stroke, the new charge will be ignited, and thus the foregoing cycle of operation will be completed. f

I he operation of the pistons 18 and 17 is identical with that of the pistons 4 and 3, excepting that the operations take place 180 later. By particular reference to Fig. 7, it will be observed that the cycle of operation of the high pressure p iston isras follows: Commencing the cycle with the high pressure cylinder filled with a compressed charge of fuel ready t0 be ignited and the high pressure piston to vbegin itsv down stroke. During the down stroke of the high pressure piston it will operate as an internal com'- buetion engine under the influence of the ignited new charge. On its first up-stroke it will serve to compress 'the air that has been drawn into the high pressure cylinder. On itssecond 4down stroke 1t will operate as a hot air engine, under the influence of the expanding heated: air, (the air having been warmed bythe heat drawn out of the cylinde'r walls) and on its second up stroke it serves to compress the air `that has been drawn into the cylinder plus the new charge lof fuel that has been pumped into the cylinder bythe fuel pump. The cycle of operation of the low pressure piston begins 45 after the beginning of the cycle of the high pressure piston.- 'During the iirst halfof its down stroke it works under the influence of the expanding old air charge plus lthe eiryploded charge of the high pressure cylinder,

when' the cylinders 1 and 2 are in communi cation with'theduct l2. During the second half of itsdown stroke, the low pressure piston draws the spent charge from the high .pressure cylinder into the low pressure cylinder and draws air into the'high pres-I sure' cylinder through the piston-controlled ports of the same; during'three fourths lof the tip-stroke of the low pressure piston, it exhausts the old charge in the low pressure cylinder and during the remaining part of the up-stroke itcompressesv thel residual charge of air plus the air Ythat is pumped into it, via the duct 12 from the 'airfpump During the seconddown stroke of thev low pressure cylinder ityworksclirst under the influence of the expanding aircharge, 'as'v a vhot air'. engine, and secondly, it draws the air from the high pressure cylinder into the `low pressure cylinder and draws air into the high pressure cylinder through the pistoncontrolled ports of the same. vDuring the first part of the 'second up-stroke of the low pressure piston it exhausts the supply of air, and during the second part of the up-stroke it compresses the old residual air charge plus the new charge of air pumped into the cylinder bythe 'air pump. From the foregoing, it will be seen that on every other down stroke of the high'pressure piston, it operates as an internal combustion engine, and on the other 'down strokes it operates as -a hot air engine. Similarly the low pressure piston` on `alternate down strokes operates under the iniiuence of exploded new charge, as an internal combustion engine,asit were, and on the other down strokes it operates as a hot air engine under the influence of the expanding air. It will therefore be seen that I have provided a four-cycle compound 'engine in which each ofthe pistons operate 'under the four-stroke cycle, but I obtain a v workingimpulse on-each down stroke, one .of the impulses being given when the piston is working as an internal combustion engine, andpthe other impulse being given vwhen the piston is working as a hot air engine, thus obtaining the benefits of a vtwo-cycle engine 'in a fourcycle engine.

particular type of ignition system, as any of the approved types now well known in the art, maybe employed; either a hot tube or electric ignition, as conditions make desirable, the only requirement being Athat the ignition system be. timed to ignite the'new charges in the high ressure cylindersat the proper intervals, a t ing that can be readily done by mere mechanical adjustment ofthe present ignition systems to my engine, and I therefore do not think it necessaryf'to disclose any ignition system.

From the foregoing description taken in ings, it is thought the complete construction,

will be readily understood by those skilled in theart towhichthe invention appertains, and I desire it understood that4 slight changes in the operation and arrangement of the parts may be made.; ,In other words, the cranks may not be set'- 45 apart, they may `be set at 35?, 01'50" apart, or other slight variations of like nature may be readily made without vdeparting from the spirit of .the invention, or the scope of the appended claims.

What I claim is 1. The .method of operating compound engines of the type described, havin a high and `'low pressure cylinder and t e1r pistons, which consists in impelling the high pressurepiston on alternate Worklng strokes c'nnection with the accompanying drawl operation and advantages of my i'iwentionI In: th1s-application I have disclosed no by an ignited iinpelling said high pressure piston on the other working strokes by expanding air, operating said high pressure piston on alternate compression strokes to compress air in the high pressure cylinder and on the other compression strokes to compress air and fuel mixture in said high pressure cylinder, said method consisting further in acting on the low pressure piston to perform itsrcycle of operations a predetermined number of degreesbehind the high pressure piston, said method further consists in throwing the high permit bothr pistons to be impelled by the saine working agent during a coordinate part of their working strokes.

2. The method of ternal combustion and hot'air engines of the compound-type having high and low pressure cylinders and pistons, which consists in throwing th two cylinders into communication at regular intervals and operating the low pressure piston to withdraw a spent charge from the high pressure cylinder twice during each cycle of. opera-tion of the pistons and simultaneously draw air into the high pressure cylinder; and which consists further in operating said high pressure piston to move on its compression stroke to compress the contents of the high pressure cylinder; and which consists. in admitting a chai'ge of fuel into the high pressure cylinder during alternate compression strokes of the high pressure piston.

3. The method of operating combined internal combustion and hot air engines of the compound type having high and low pressure cylinders and pistons,which consists in throwing the two cylinders into communication at regular intervals and'operating the "low pressure `piston Vtowithdraw 'a spent charge t from the .high pressure cylinder twice during each cycle of operation of the pistons and simultaneously draw air into'the high pressure cylinder; and which consists further in operating said high pressure piston to move on its compression stroke to compress cylinder; and which consists in admitting a charge of fuel into the high pressure cylinder during alternate compression strokes of the high pressure piston, and which consists further in impellingby a common working charge in simultaneously during a common part of their cycle of movement.

4. The method of operating combined in-` ternal combustion and hot air engines of the compound type having high and 'low preswhich consists in throwing the two cylinders into communication at regular intervals and operating the low pressure piston to withdraw a spent chargeof air and gas fuell and low pressure vcylinders intoD communication at the regular intervals tooperating combined inthe contents of the high pressure both cylinders, both pistons" charge from the high pressure cylinder twice during each cycle of operation of the pistons and'simultaneously draw air' into the high pressure cylinder; and which consists further in operating said high pressure piston tomove on its compression stroke to compress the contents of the high pressure cylinder; and which consists in admitting a charge of fuel into the high pressure cylinder during alternate compression strokes of the high pressure piston, and which consists further in impelling, by a common working charge in both cylinders, both pistons to cause them to move together during a common part of their cycle of movement, and which consists furtherin forcing air into the low pressure cylinder during the exhausting strokes 'of the low pressure piston and operating thev low pressure piston to compress such air. Y

5. The method of operating combined internal combustion and hot air engines of the compound type having high and low pressure'cylinders and pistons, which consists in throwing the two `cylinders into communication vat regularintervals and operating the low pressure piston to withdraw a spent charge from the high pressure cylinder twice during each cycle of operation of the pistons and simultaneously draw air into the high ressure cylinder; and which consists 'furt er in moving said hi h pressure cylinder on a compression stro e to compress the contents of said high pressure cylinder; and which consists in admitting a charge of fuel into the high pressure cylin- 4der .during alternate compression strokes of the high pressure piston, and consists further in forcing air into `the lowpressure cylinder during each exhausting stroke of the low pressure piston to draw out the heat from the cylinder walls, and consists fur- -ther in operating said low pressure piston to compress such air in the low pressure cylinder.

6. The method of operatingv engines of the type described, which consists in taking a high pressure cylinder and its piston and a low pressure cylinder and its piston, and operating on the high pressure piston to cause it to undergo the following cycle of operat1on,`,to wit z-on one down stroke operating said high pressure piston to work under an ignited charge of air and gas; on the first up stroke thereafter, operating said high pressure piston to compress a'charge of fresh air into said high pressure cylinder; on the next down stroke operating said high pressure piston to act as a hot air engine underl the influence' of the expandingair; and on the next up stroke operating said high pressure piston to compress a charge of fresh air, and then vforcing fuel gas into said high `.pressure cylinder, and subsequently operatizo iso

press the gas; said method consistingfurther in putting said low pressure piston through the following cycle of operations,v

commencing a predetermined period after the beginning of the cycle of the high pressure piston to wit-on the first part of its down stroke operating said high pressure piston to act under an expanding old air charge and residual exploded mixture admitted from the high pressure cylinder, and on the last part of its down stroke, operating said high pressure piston to draw the spent charge from the high pressure cylinder into the low pressure cylinder and simultaneously supply the high pressure cylinder with fresh air, then operating the low pressure piston on its first up stroke to exhaust a predetermined part ofthe low pressure cylinder contents to atmosphere and compress the remainder in the loW pressure cylinder, and,

on the first part of the second down stroke, cause said low pressure piston to operate under the influence of the expanding residual charge and the charge of hot air from the high pressure cylinder', and on thelast part of its second down stroke causing said low pressure piston to operate to draw the contents of the high pressure cylinder into the low pressure cylinder, and recharge the high pressure cylinder With fresh air; and on its second up stroke causing said low pressure piston to operate to exhaust a predetermined part of the contents of the low pressure cylinder to atmosphere and compress the remainder.

7. The method of operating engines'of the type described, which consists in taking a high pressure cylinder and its piston and a low pressure cylinder and its-piston, and putting the hign pressure piston through the following cycle of operation, to wit onA one down stroke operating said high pressure piston to work under an ignited charge of air and gas; on the first up stroke thereafter, operating said high pressure piston to compress a charge of fresh air into said high pressure cylinder; on the next down stroke operating said high pressure piston to -act as a hot air engine under the influence of the expanding air; and on the next up stroke operating said high pressure piston to compress a charge of fresh pair, and after forcing fuel gas into said high pressure cylinder and moving said high pressure piston to also compress the same; said method consists further in putting said low pressure piston through the following cycle of opera` tions, commencing a predetermined period after the beginning of the cyele of the high pressure piston to ivihfon the first part of its down stroke .operating said hie-h pressure piston to act lunder an expanding old air charge and residual exploded mixture admitted from the`high pressure cylinder-4 ing said high pressure 'piston to draw the spent charge from the high pressure cylinder into the low pressure cylinder and simultaneously supply the high pressure cylinder with fresh air; then moving the lo-W pressure piston onfits first up stroke to exhaust a predetermined part of the loW pressure cylinder contents to atmosphere and colnpress the remainderA in the low pressure cylinder; and on the first part of' the second down stroke moving said 10W pressure piston by the expanding residual charge and "the charge of lsot air from the high pressure cylinder, and moving said low pressune piston on the last part of its second down stroke to draw the contents of the high pressure cylinder into the low pressure cylinder, and recharge the high pressure cylinder With fresh air, and moving said lowpressure piston,on itsl second up stroke to exhaust a predetermined part of the contents of the ldw pressure cylinder to atmosphere and conipress the remainder; said method consisting further in conveying air into the loW pressure cylinder during the compressing portion of the up strokes of the lonT pressure piston.

8. In an engine of the class described, a high pressure cylinder and its piston, a low pressure piston and its cylinder; a crank shaft to Which said pistons are connected,

ports; said lowpressure cylinder having an exhaust port; an exhaust valve controlling said exhaust port; an mtercommumcating duet connecting said cylinders; a valve ing said duct; an air pump; a duet between said pump and said intercommunicating duet; means for operating said'pump' in time to force air through said ducts into said low pressure cylinder during the up stroke of said low pressure piston; said pistons moving down in unison during a part of ltheir downst'roke; means for holding said intercommunicating valve open during the common portion of the down stroke of said pistonsl and the remaining portion of the down stroke of said low pressure piston, to throw both cylinders into communication; said low pressure piston operating to draw-the contents of said high pressure cylinder into said low pressure cylinder and replace the same with air before said intercommunieating valve closes and after said air inlet ports are open; means for opening said exhaust valve as said low-pressure piston moves on its up stroke to exhaust the contents of the low pressure cylinder to atmosphere and again closing said exhaust valve before said low pressurev piston completes its up stroke, thereby causing said loiv pressure piston during the remaining portion of its up stroke to cempressthe residual contents of the low pressure cylinder and means duct between the respective high and low valve for each inter-l pressure cylinders, a communicating duct, an exhaust port- 'for each low pressure cylinder and an exhaust valve for controlling each exhaust port, a

common air pump for forcing .air into the interconimunicatiiig ducts of' the respective units during each up stroke of the respective 'low pressure pistons and a common fuel pump for forcing fuel into the high pressure cylinders and including means for rendering saidfuel. pump inoperative during the alternate up or compression'strokes of the respective high pressure pistons to cause said fuel pump to `inject fuel into the high pressure cylinders on `alter-nate compression strokes of the respective high pressure pistons, valve gear for actuating said exhaust valve to hold the same open during a predetermined part of the exhausting stroke of the low pressure pistons and holdsaid eX- haust valves closed while said air pump is forcing air into said low pressure cylinders, and a valve gear for operating valves to hold the same open during the down stroke of the low pressure pistons,`said highpressure cylinders having piston controlled air inlet ports opening as said high pressure pistons reach the lowest limit of their strokes while said intercommunicating valves are open.

10. In an internal combustion engine, highv and low pressure cylinders and their pistons, means coperative therewith for admitting air and gas fuel charges into said high pres-\ sure cylinder on alternate working strokes, means for igniting said charges to impe] Y said high pressurepiston, means for admitting air into said high pressure cylinder on -the other working strokes to take up the heat of the cylinder walls and piston and on expanding impel said high pressure piston,

said high pressurepiston operating ,onalternate compression strokes to compress the air in the high pressure cylinder -and on the other compression strokes compress the air and fuel mixture in said high pressure cylindcr, means connecting said pistons to cause saidlow pressure piston to perform its cycle of operations a predetermined number of degrees beliindthe high pressure piston,A means for throwing the high and low pressure pistons into communication at regular intervals to permit both pistons to be iinpelled by the sar'ne working agent during' a c'ordinate part of` their working strokes.

11. A combined internal combustion iand hot air engine of the compound type, said engine including high and low pressure cyl- -inders and'their pistons, a crank shaft, connecting rods betweehsaid pistons and crank shaft, said low pressure piston being connected to the crank shaft to perform its cycleA of operation a predetermined number o f degrees behind the high pressure piston, means for opening upy communication between` the two 'cylinders at regular intervals to permit the low pressurepiston to withdraw a spent charge from the high pressure cylinder twice during each cycle of the operation of the pistons and simultaneously draw air into the high pressure cylinder, said high pressure piston operating on its compression strokes to compress the contents of said high pressure cylinder, and means forvadmitting a charge of fuel into the high pressure cylinder during alternate compression strokes' of the high pressurepiston,

-12. A combinedinternal combustion and hot air-engine of the compound type, said engine including high and low pressure cylinders and their pistons, a crank shaft, connecting rods between `said pistons and crank shaft, said low pressure piston being connectedv to the crank shaft to perform its cycle of operation a predetermined number ofdel,f ,rreesbehind the high pressure piston, means for opening up communication between the two cylindersat regular intervals to permit the low pressure piston to withdraw a spent charge from the high pressure cylinder twice v to compress the contents of said high pressure cylinder` and means for admit-ting a charge of fuel into the high pressure cylinder' during alternate compression strokes of the high pressure'piston, said means that throws the two cylinders into communication at times, also operating to throw said `cylinders into communication at predeter- -mined times to cause both pistons to be impelled by a common working charge in both cylinders, during-the common part of their cycle of operations.

18. A combined internal combustion and hot air engine-of the compound ty`pe, said engine including high and low pressure cylinders and their pistons, a crank shaft, connecting rods between said pistonsand vcrank shaft, said low pressure piston being connected to the crank shaft to perform lits cycle of peration a predetermined number of degrees behindthe high pressure piston, means for opening up communication between the two cylinders at regular intervals to permit the low pressure piston to withdraw u spent charge from the high pressure cylinder twice during each cycle of the op*- eration of the pistons and simultaneously draw air into lche high pressure cylinder, said high pressure piston operating on its compression strokes to compress the contents of said high pressure cylinder, and means for admitting a chirgeof fuel into the high vpressure cylinder during alternate compression strokes of the high pressure piston, said meansl that throws the two cylinders into communication at times, also operating to throw said cylinders into communication at predetermined times to cause both pistons -to be impelled by ai common Working charge 15 in both cylinders, during the common part of their cycle of operations, and means for forcing air into the 10W pressure cylinder during the exhausting strokes of the low pressure vpiston to be compressed by said loW 20 pressure piston on its compression stroke.

. WM. J. WRIGHT.

Witnesses: l

FRED G. DIETERICH, ALBERT E. DIETERICH. 

